1. The Field of the Invention
The present invention relates generally to the operation of devices in wireless networks. More particularly, embodiments of the invention relate to systems and methods for generating neighbor lists used by devices operating in wireless networks.
2. The Relevant Technology
The convenience and utility of wireless devices including cellular phones is undeniable. As technology continues to improve, cellular phone users are increasingly expecting more from their wireless network. Whenever a user has an adverse experience with a wireless network such as being unable to access the wireless network or experiencing a dropped call, the user is inconvenienced and unsatisfied with the performance of the wireless network. As a result, providers of wireless networks often strive to ensure that a wireless device has access to their wireless network and to ensure that adverse experiences such as dropped calls do not occur.
To achieve these goals, a wireless provider typically deploys multiple towers in the wireless network in a manner that is intended to provide satisfactory coverage. The towers are hopefully arranged in a manner that ensures, regardless of where a particular device is located in the wireless network, that the particular device has access to the network without experiencing problems such as a dropped call or weak signal.
One of the key features of wireless devices is that they are mobile in nature and are therefore unlikely to remain in the same location, even during a single call. People often use their wireless devices, for example, as they travel within the network. Because of this movement, a user may move out of the range of a particular tower. The need to switch the call over to another tower therefore arises. One of the factors that complicates this switching process is that the towers used by devices in the network are often approached using different paths and from multiple directions. As a result, the process of handing off a call from one tower to another can be complicated.
One of the ways that a wireless provider ensures that a call can be switched from one tower to the next and therefore ensure that the call is not dropped is through the use of neighbor lists. During a call from a wireless device, the primary sector of a tower may provide the wireless device with a neighbor list. The neighbor list identifies other towers or tower sectors that the wireless device may encounter during the call. As the device changes from one primary sector to a new primary sector, the neighbor list is updated or replaced by the new primary sector. The neighbor list becomes an important aspect of ensuring that a wireless network provides quality service to users.
Unfortunately, one of the common problems experienced in wireless networks is related to the neighbor list. A neighbor list that does not adequately describe or identify the towers or tower sectors that wireless devices may encounter during use will lead to problems such as dropped calls and to customer dissatisfaction. The generation of a neighbor list, however, is not a trivial exercise. There are many factors that make it difficult to identify the tower sectors that should be included in the neighbor list of a given sector. Variable radio propagation due to contributing factors such as terrain, deployment errors, power changes, and load based changes are examples of factors that can impact the tower sectors that a wireless device might encounter.
As a result, the neighbor lists actually delivered to wireless devices do not necessarily include all of the appropriate neighbors of the primary tower sector currently being used. Further, because users are traveling in different directions and in different paths with respect to primary sectors, each device is typically exercising a different portion of the primary sector's neighbor list.
Neighbor list problems can be very difficult to resolve via field testing because of all the possible paths and directions of travel that correspond to real world device usage. Because there are multiple paths and directions of travel, different parts of any given neighbor list can be exercised. Thus, neighbor list problems continue to create various problems in a wireless network that are difficult to resolve.
While the fact that a particular tower sector is not included on a neighbor list may seem inconsequential, it in fact can disrupt the use of a cellular device. For example, assume that there is a tower sector that is not currently on a neighbor list of a wireless device. If this tower sector becomes a strong radio source due to environmental changes or other factors, then it is likely that the cellular communication will be lost or dropped due to interference from the missing neighbor. In other words, tower sectors that are not included in a neighbor list can interfere with existing communications and cause calls to be lost or cause other problems. For these and other reasons, neighbor list errors can disrupt cellular service in addition to inconveniencing users. Systems and methods are therefore needed to reduce neighbor list errors as well as to more effectively identify ideal neighbor lists for the tower sectors in a wireless network.